Park Systems - ICM Image of Suspended Collagen Fibrils
Ion conductance microscopy (ICM)1 is useful for obtaining contact-free images of the surface topography and has been used for imaging cultured cells under liquid conditions
Tatsuo Ushiki and Masato Nakajima (Niigata University, Japan)
Ion conductance microscopy (ICM)1 is useful for obtaining contact-free images of the surface topography and has been used for imaging cultured cells under liquid conditions2. The approach-retract scanning (ARS) mode is a new mode of ICM, which is especially powerful for imaging samples with steep slopes3. To examine the applicability of the ARS mode for imaging biological samples with greater height gaps, dense collagen fibril networks were examined by ICM4.
Collagen fibrils were obtained from the tail tendon of adult Wistar rats and stored in physiological saline with 1-10 % tymol (2-isopropyl-5-methylphenol) at 4 °C for a minimum of 1 day. A small piece of the tendon was then stretched on the surface and air dried overnight, followed by immersion of the sample in physiological saline. ICM imaging was made in the ARS mode using XE-Bio System
Figure 1 is an example of ICM imaging of collagen fibril networks using the ARS mode. The width of the individual fibrils varied from 50 to 470 nm. The section profile also showed that the width of the collagen fibril indicated by green arrows was 277 nm and the height difference between the glass surface and the fibril was 2606 nm. This result indicates that some fibrils are suspended over the glass substrate during scanning for ICM imaging. Thus, the ARS mode of ICM has the advantage of minimizing (or free from) the loading force, which is unavoidable in AFM.
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3P. Novak, C. Li, A. I. Shevchuk, R. Stepanyan, M. Caldwell, S. Hughes, T. G. Smart,, et al.. Nat. Methods 6, 279 (2009).
4T. Ushiki, M. Nakajima, M. Choi, S.-J. Cho, F. Iwata. Micron (2012, in press)